In attempting to understand the fundamental neurobiology of social behavior, a primate animal model would be ideal. The bonnet macaque (Macaca radiata) is a particularly good example of a species of nonhuman primate that exhibits a range of sophisticated social behaviors. In this proposal, we propose a collaboration between a biobehavioral primatology laboratory and a clinical neuroimaging group to explore, develop, and implement methods that would allow for the study of specific neurobiological substrates modulating aspects of primate social behavior. First, we plan to conduct baseline magnetic resonance imaging studies, including volumetric analyses, magnetic resonance spectroscopy, and diffusion tensor imaging, in 24 bonnets early in development in order to characterize a profile of brain structure and function which is reflected in social performance. The major region of interest is the corpus striatum, reflecting a convergence of evidence of this region's role in modulating brain reward pathways, which might subserve a primate's reinforcement to engage in social activity. Second, to assess social behavior, we will develop a series of video simulations of social interactions that can be used to test bonnets' differentiable responsivity, enabling the study of social behavior under controlled and quantifiable conditions. The study's main hypotheses are that there will be a continuum of striatal pathology among the 24 bonnets as measured by the 3 imaging modalities, and those bonnets who display the most pathological imaging profiles will display less social engagement when confronted with live social interactions than when confronted with social video encounters. If confirmed, this suggests that abnormal striatal "viability" impedes a primate's overall social dexterity and drive for social interaction. A secondary aim of this project is to develop an educational and future research component, which will include a research apprenticeship and opportunities for graduate and undergraduate students to work in social neuroscience-related projects. Ultimately, this knowledge will contribute to a better understanding of the biobehavioral processes related to social behavior, with relevance to disorders such as schizophrenia, social anxiety disorder, autism, and personality disorders involving disruption of interpersonal social behavior.